Control system for posture control tabs of marine vessel, marine vessel, and method for controlling posture control tabs, capable of avoiding contact of posture control tabs with foreign object

ABSTRACT

A control system for posture control tabs of a marine vessel prevents posture control tabs from coming into contact with a foreign object. The posture control tabs are mounted on a stern to control a posture of a hull. Actuators actuate the respective posture control tabs. When it is judged that that the hull is being loaded onto a trailer or it is detected that the hull has entered a speed restriction zone, a controller controls the actuators to position the posture control tabs at retracted positions.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to Japanese PatentApplication No. 2019-200520 filed on Nov. 5, 2019. The entire contentsof this application are hereby incorporated herein by reference.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to control systems for posture controltabs, marine vessels, and methods for controlling the posture controltabs of the marine vessel, which are each able to avoid contact of theposture control tabs with a foreign object.

2. Description of the Related Art

Conventionally, marine vessels equipped with posture control tabs liketrim tabs for changing the posture of a hull as disclosed in U.S. Pat.No. 8,261,682 and Zipwake “Dynamic Trim-Control System” (URL:http://www.zipwake.com; hereafter referred to merely as Zipwake) areknown. Posture control tabs are mounted on the stern of a hull such thatthey are able to, for example, swing with respect to or project from aretracted position at which they are not in use. When a marine vessel istransported on land, the marine vessel is typically loaded onto atrailer. To load a marine vessel on a trailer at the shore, the hull ofthe marine vessel is usually tilted so the bow can rise.

However, there may be a case in which a marine vessel is loaded onto atrailer with the posture control tabs in a down position. For example,there may be a case in which the posture control tabs have been manuallylowered before the marine vessel is loaded onto the trailer. Also, theremay be a case in which the posture control tabs have been lowered duringsailing in a posture-control mode in which the posture control tabs areautomatically controlled. If a marine vessel is loaded onto a trailerwith the posture control tabs down, and the bow rises, the posturecontrol tabs mounted on the stern may come close to a foreign objectsuch as a rail of the trailer, the ground, or the sea bottom. There isroom for improvement from the viewpoint of avoiding contact of theposture control tabs with the foreign object.

SUMMARY OF THE INVENTION

Preferred embodiments of the present invention provide control systemsto control posture control tabs of a marine vessel, marine vessels, andmethods for controlling the posture control tabs of the marine vessel,which are each able to avoid contact of the posture control tabs with aforeign object.

According to a preferred embodiment of the present invention, a controlsystem includes posture control tabs mounted on a stern to control aposture of a hull of a marine vessel, and actuators to actuate theposture control tabs. The control system further includes a centralprocessing unit configured or programmed to define and function as ajudgment unit to judge whether or not the hull is being loaded onto atrailer, and a processor to, upon the judgment unit judging that thehull is being loaded onto the trailer, control the actuators to positionthe posture control tabs at retracted positions.

According to another preferred embodiment of the present invention, acontrol system includes posture control tabs mounted on a stern tocontrol a posture of a hull of a marine vessel and actuators to actuatethe posture control tabs. The control system further includes a centralprocessing unit configured or programmed to define and function as adetection unit to detect whether or not the hull has entered a speedrestriction zone, and a processor to, upon the detection unit detectingthat the hull has entered the speed restriction zone, control theactuators to position the posture control tabs at retracted positions.

According to another preferred embodiment of the present invention, amarine vessel includes a hull, and one of the above-described controlsystems.

According to another preferred embodiment of the present invention, amethod controls posture control tabs of a marine vessel, wherein themarine vessel includes posture control tabs mounted on a stern tocontrol a posture of a hull, and actuators to actuate the posturecontrol tabs. The method includes judging with a judgment unit whetheror not the hull is being loaded onto a trailer, and upon the judgmentunit judging that the hull is being loaded onto the trailer, controllingwith a processor the actuators to position the posture control tabs atretracted positions.

According to another preferred embodiment of the present invention, amethod controls posture control tabs of a marine vessel, wherein themarine vessel includes posture control tabs mounted on a stern tocontrol a posture of a hull, and actuators to actuate the posturecontrol tabs. The method includes detecting with a detection unitwhether or not the hull has entered a speed restriction zone, and uponthe detection unit detecting that the hull has entered the speedrestriction zone, controlling with a processor the actuators to positionthe posture control tabs at retracted positions.

According to preferred embodiments of the present invention, when it isjudged that the hull is being loaded onto the trailer or it is detectedthat the hull has entered a speed restriction zone, the actuators arecontrolled so that the posture control tabs that control the posture ofthe hull are positioned at the retracted position. As a result, theposture control tabs do not come too close to a foreign object such as arail of the trailer when being loaded onto the trailer, and thus contactof the posture control tabs with a foreign object is avoided.

The above and other elements, features, steps, characteristics andadvantages of the present invention will become more apparent from thefollowing detailed description of the preferred embodiments withreference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top view of a marine vessel to which a posture controlsystem for posture control tabs according to a preferred embodiment ofthe present invention is provided.

FIG. 2 is a side view of a trim tab unit attached to a hull.

FIG. 3 is a block diagram of a maneuvering system.

FIG. 4 is a side view of a marine vessel being transported on land.

FIG. 5 is a flowchart of a trim tab retracting process.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, preferred embodiments will be described with reference tothe drawings.

FIG. 1 is a top view of a marine vessel to which a control system forposture control tabs according to a referred embodiment of the presentinvention is provided. The marine vessel 11 includes a hull 13, aplurality of outboard motors (for example, two outboard motors 15A,15B), which define and function as marine propulsion devices mounted onthe hull 13, and a plurality of trim tab units (for example, a pair oftrim tab units 20A, 20B). A central unit 10, a steering wheel 18, and athrottle lever 12 are provided in the vicinity of a cockpit in the hull13.

In the following description, a fore-and-aft direction, a crosswisedirection, and a vertical direction refer to a fore-and-aft direction, acrosswise direction, and a vertical direction, respectively, of the hull13. For example, as shown in FIG. 1, a centerline C1 extending in thefore-and-aft direction of the hull 13 passes through the center ofgravity G of the marine vessel 11. The fore-and-aft direction is thedirection along the centerline C1. Fore or front refers to the directiontoward the upper side of the view along the centerline C1. Aft or rearrefers to the direction toward the lower side of the view along thecenterline C1. The crosswise direction is defined based on a case inwhich the hull 13 is viewed from the rear. The vertical direction isvertical to the fore-and-aft direction and the crosswise direction.

The two outboard motors 15A and 15B are mounted on a stern of the hull13 side by side. To distinguish the two outboard motors 15A and 15B, theone located on the port side is referred to as the “outboard motor 15A”,and the one located on the starboard side is referred to as the“outboard motor 15B”. The outboard motors 15A and 15B are mounted on thehull 13 via mounting units 14A an 14B, respectively. The outboard motors15A and 15B include engines 16A and 16B, respectively, which arepreferably internal combustion engines. The outboard motors 15A and 15Bgenerate propulsive forces to move the hull 13 by using propellers (notillustrated) that are turned by driving forces of the correspondingengines 16A and 16B.

The mounting units 14A and 14B each include a swivel bracket, a clampbracket, a steering shaft, and a tilt shaft (none of which areillustrated). The mounting units 14A and 14B further include power trimand tilt mechanisms (PTT mechanisms) 23A and 23B, respectively (FIG. 3).The PTT mechanisms 23A and 23B turn the corresponding outboard motors15A and 15B about the tilt shaft. This makes it possible to change aninclination angle of the outboard motors 15A and 15B with respect to thehull 13, and thus a trim adjustment to be made, and the outboard motors15A and 15B are tilted up and down. Moreover, each of the outboardmotors 15A and 15B is able to turn about a turning center C2 (about thesteering shaft) with respect to the swivel bracket. Operating thesteering wheel 18 causes each of the outboard motors 15A and 15B to turnabout the turning center C2 in the crosswise direction (direction R1).Thus, the marine vessel 11 is steered.

The pair of trim tab units 20A and 20B are mounted on the stern on theport side and the starboard side such that they are able to swing abouta swing axis C3. To distinguish the two trim tab units 20A and 20B fromeach other, the one located on the port side is referred to as the “trimtab unit 20A”, and the one located on the starboard side is referred toas the “trim tab unit 20B”.

FIG. 2 is a side view of the trim tab unit 20A attached to the hull 13.The trim tab units 20A and 20B have the same construction, and thus aconstruction of only the trim tab unit 20A will now be described as arepresentative example. The trim tab unit 20A includes a trim tabactuator 22A and a tab 21A. The tab 21A is attached to the rear of thehull 13 such that it is able to swing about the swing axis C3. Forexample, the proximal end of the tab 21A is attached to the rear of thehull 13, and the free end of the tab 21A swings up and down (in aswinging direction R2) about the swing axis C3. The tab 21A is anexample of a posture control tab that controls the posture of the hull13.

The trim tab actuator 22A is disposed between the tab 21A and the hull13 such that it connects the tab 21A and the hull 13 together. The trimtab actuator 22A actuates the tab 21A to swing it with respect to thehull 13. It should be noted that the tab 21A indicated by a chaindouble-dashed line in FIG. 2 is at a position where its free end is atthe highest level (a position at which the amount of lowering of the tab21A is 0%), and this position corresponds to a retracted position. Thetab 21A indicated by a solid line in FIG. 2 is at a position where itsfree end is at a lower level than a keel at the bottom of the marinevessel 11. It should be noted that a range in which the tab 21A is ableto swing is not limited to the one illustrated in FIG. 2. The swingingdirection R2 is defined with reference to the swing axis C3. The swingaxis C3 is perpendicular or substantially perpendicular to thecenterline C1 and parallel or substantially parallel to, for example,the crosswise direction. It should be noted that the swing axis C3 mayextend diagonally so as to cross the turning center C2.

FIG. 3 is a block diagram of a maneuvering system. The maneuveringsystem includes a control system for the posture control tabs accordingto the present preferred embodiment. The marine vessel 11 includes acontroller 30, a throttle position sensor 34, a steering angle sensor35, a hull speed sensor 36, a hull acceleration sensor 37, a posturesensor 38, a receiver 39, a display unit 9, and a setting operation unit19. The marine vessel 11 also includes engine rpm detectors 17A and 17B,turning actuators 24A and 24B, the PTT mechanisms 23A and 23B, the trimtab actuators 22A and 22B (see FIG. 2 as well).

The controller 30, the throttle position sensor 34, the steering anglesensor 35, the hull speed sensor 36, the hull acceleration sensor 37,the posture sensor 38, the receiver 39, the display unit 9, and thesetting operation unit 19 are included in the central unit 10 ordisposed in the vicinity of the central unit 10. The turning actuators24A and 24B and the PTT mechanisms 23A and 23B are provided for therespective outboard motors 15A and 15B. The engine rpm detectors 17A and17B are provided in the respective outboard motors 15A and 15B. The trimtab actuators 22A and 22B are included in the trim tab units 20A and20B, respectively.

The controller 30 includes a CPU 31, a ROM 32, a RAM 33, and a timerwhich is not illustrated. The ROM 32 stores control programs. The CPU 31loads the control programs stored in the ROM 32 into the RAM 33 toimplement various types of control processes. The RAM 33 provides a workarea for the CPU 31 to execute the control programs.

Results of detection by the sensors 34 to 39 and the engine rpmdetectors 17A and 17B are supplied to the controller 30. The throttleposition sensor 34 detects the opening angle of a throttle valve, whichis not illustrated. The steering angle sensor 35 detects the turningangle of the steering wheel 18. The hull speed sensor 36 and the hullacceleration sensor 37 detect the speed and acceleration, respectively,of the marine vessel 11 (the hull 13) while it is traveling.

The posture sensor 38 includes, for example, a gyro sensor, a magneticdirection sensor, and so forth. Based on a signal output from theposture sensor 38, the controller 30 calculates a roll angle, a pitchangle, and a yaw angle of the hull 13. It should be noted that thecontroller 30 may calculate the roll angle and the pitch angle based ona signal output from the hull acceleration sensor 37. The receiver 39includes a GNSS (Global Navigation Satellite Systems) receiver such as aGPS and includes a function of receiving GPS signals and various typesof signals as positional information. From a speed restriction zone orland in the vicinity of the speed restriction zone, an identificationsignal providing notification that the area is a speed restriction zoneis transmitted. The speed restriction zone refers to an area in a harboror the like in which is required to limit the speed of a marine vesselto a predetermined speed or lower. The receiver 39 also includes afunction of receiving the identification signal. It should be noted thatthe acceleration of the hull 13 may also be obtained from a GPS signalreceived by the receiver 39.

The engine rpm detectors 17A and 17B detect the number of revolutions ofthe respective engines 16A and 16B per unit time (hereafter referred toas “the engine rpm N”). The display unit 9 displays various types ofinformation. The setting operation unit 19 includes an operator that avessel operator uses to perform operations relating to maneuvering, aPTT operating switch, a setting operator that a vessel operator uses tomake various settings, and an input operator that a vessel operator usesto input various types of instructions (none of which are illustrated).

The turning actuators 24A and 24B turn the respective outboard motors15A and 15B about the turning center C2 with respect to the hull 13.Turning the outboard motors 15A and 15B about the turning center C2changes the direction in which a propulsion force acts on the centerlineC1 of the hull 13. The PTT mechanisms 23A and 23B tilt the respectiveoutboard motors 15A and 15B with respect to the clamp bracket by turningthe respective outboard motors 15A and 15B about the tilt shaft. The PTTmechanisms 23A and 23B are operated in response to, for example,operation of the PTT operating switch. As a result, the inclinationangle of the outboard motors 15A and 15B with respect to the hull 13 ischanged.

The trim tab actuators 22A and 22B are controlled by the controller 30,more specifically, by a processor in the CPU 31 within the controller30. For example, the trim tab actuators 22A and 22B operate in responseto the controller 30 outputting control signals to them. In response tothe operation of one of the trim tab actuators 22A and 22B, acorresponding one of the tabs 21A and 21B swings. It should be notedthat actuators used for the PTT mechanisms 23A and 23B and the trim tabactuators 22A and 22B may be either hydraulic or electric.

It should be noted that the controller 30 may obtain results ofdetection by the engine rpm detectors 17A and 17B via a remote controlECU, which is not illustrated. The controller 30 may also use outboardmotor ECUs (not illustrated) provided in the respective outboard motors15A and 15B, to control the respective engines 16A and 16B.

FIG. 4 is a side view showing how the marine vessel 11 is transported onland. As shown in FIG. 4, the marine vessel 11 is sometimes transportedby a motor vehicle 42 and a trailer 40. While the marine vessel 11 isbeing loaded onto the trailer 40 at the shore, the marine vessel 11 isusually tilted to raise the bow. If loading of the marine vessel 11 ontothe trailer 40 is started with the tabs 21A and 21B in a down position,the marine vessel 11 is tilted causing the tabs 21A and 21B to comeclose to a foreign object such as the sea bottom, ground, or a rail 41of the trailer 40. It is preferable to avoid contact of the tabs 21A and21B with the foreign object. Accordingly, in the present preferredembodiment, as will be described below, the controller 30 raises thetabs 21A and 21B and positions them at the retracted positions while,for example, the hull 13 is being loaded onto the trailer 40.

It should be noted that the tab 21A indicated by the chain double-dashedline in FIG. 2 is located parallel or substantially parallel to thebottom of the hull 13 (keel) in the side view. In the present preferredembodiment, the tabs 21A and 21B have only to be controlled so as toreliably prevent the trailer 40 or the like from interfering with thetabs 21A and 21B. Thus, the retracted positions to which the tabs 21Aand 21B are raised while, for example, the hull 13 is being loaded ontothe trailer 40, are not limited to the positions at which the amount oflowering of the tabs 21A and 21B is 0%, but may be positions of the tabs21A and 21B that are, for example, parallel or substantially parallel toor above the vessel's bottom. Alternatively, the retracted positions maybe positions at which the amount of lowering of the tabs 21A and 21B isequal to or greater than a predetermined amount (for example, about10%). It should be noted that when the marine vessel 11 is movedrearward, the tabs 21A and 21B may be fully raised (positioned at theretracted positions) irrespective of a currently-set control mode.

FIG. 5 is a flowchart of a trim tab retracting process. This process isimplemented by the CPU 31 loading a control program stored in the ROM 32into the RAM 33 and executing the same. This process starts when, forexample, the maneuvering system is activated. In step S101, the CPU 31,which defines and functions as a judgment unit, judges whether or notthe hull 13 is being loaded onto the trailer 40. Here, the method tojudge whether or not the hull 13 is being loaded onto the trailer 40 isnot limited, but mainly, methods described hereafter (the first toeighth methods) may be used.

First, according to the first method, based on a speed V of the hull 13and a pitch angle P of the hull 13, the CPU 31 judges whether or not thehull 13 is being loaded onto the trailer 40. The speed V is obtainedfrom a signal output from the speed sensor 36, and the pitch angle P isobtained from a signal output from the posture sensor 38. Specifically,when the conditions that the speed V is less than (<) a predeterminedspeed, and a predetermined pitch angle is less than (<) the pitch angleP are satisfied, the CPU 31 judges that the hull 13 is being loaded ontothe trailer 40.

According to the second method, based on the speed V of the hull 13 andan engine rpm N, the CPU 31 judges whether or not the hull 13 is beingloaded onto the trailer 40. The engine rpm N is obtained from the enginerpm detectors 17A and 17B. It should be noted that an engine targeted inobtaining the engine rpm N may be either one or both of the engines 16Aand 16B (the same holds for the methods described below). For example,the CPU 31 may use either a higher one or a lower one of the engine rpmN of the engine 16A and the engine rpm N of the engine 16B.

Specifically, when the conditions that the speed V is less than (<) thepredetermined speed, and the predetermined rpm is less than (<) theengine rpm N are satisfied, the CPU 31 judges that the hull 13 is beingloaded onto the trailer 40. Alternatively, the CPU 31 may calculate adegree of change ΔN in the engine rpm N from the engine rpm N throughintegration calculation or the like, and when the conditions that thespeed V is less than (<) the predetermined speed, and the predetermineddegree of change is less than (<) the degree of change ΔN are satisfied,the CPU 31 may judge that the hull 13 is being loaded onto the trailer40.

According to the third method, based on a throttle opening angle TH ofthe engines 16A and 16B and the speed V of the hull 13, the CPU 31judges whether or not the hull 13 is being loaded onto the trailer 40.The throttle opening TH is obtained from the throttle position sensor34. It should be noted that an engine targeted in obtaining the throttleopening angle TH may be either one or both of the engines 16A and 16B(the same holds for the methods described below). For example, the CPU31 may use either a higher one or a lower one of the throttle openingangle TH of the engine 16A and the throttle opening angle TH of theengine 16B or may use an average of both, to obtain the throttle openingangle TH to be used for the judgment. Specifically, when the speed V hasnot exceeded a predetermined speed for a predetermined period of timesince the throttle opening angle TH became greater than a predeterminedopening angle (the predetermined angle< the throttle opening angle TH),the CPU 31 judges that the hull 13 is being loaded onto the trailer 40.

According to the fourth method, based on an acceleration A of the hull13 and the pitch angle P of the hull 13, the CPU 31 judges whether ornot the hull 13 is being loaded onto the trailer 40. The acceleration Ais obtained from, for example, the hull acceleration sensor 37.Specifically, when the conditions that the acceleration A is less than(<) a predetermined acceleration, and a predetermined pitch angle isless than (<) the pitch angle P are satisfied, the CPU 31 judges thatthe hull 13 is being loaded onto the trailer 40.

According to the fifth method, based on the acceleration A of the hull13 and the engine rpm N, the CPU 31 judges whether or not the hull 13 isbeing loaded onto the trailer 40. Specifically, when the conditions thatthe acceleration A is less than (<) a predetermined acceleration, and apredetermined engine rpm is less than (<) the engine rpm N aresatisfied, the CPU 31 judges that the hull 13 is being loaded onto thetrailer 40. It should be noted that as with the second method, thedegree of change ΔN in the engine rpm N may be used in place of theengine rpm N.

According to the sixth method, based on the throttle opening angle TH ofthe engines 16A and 16B and the acceleration A of the hull 13, the CPU31 judges whether or not the hull 13 is being loaded onto the trailer40. Specifically, when the acceleration A has never exceeded apredetermined acceleration for a predetermined period of time since thethrottle opening angle TH became greater than a predetermined openingangle (the predetermined angle< the throttle opening angle TH), the CPU31 judges that the hull 13 is being loaded onto the trailer 40.

According to the seventh method, based on the throttle opening angle THof the engines 16A and 16B and the pitch angle P of the hull 13, the CPU31 judges whether or not the hull 13 is being loaded onto the trailer40. Specifically, when a predetermined pitch angle is less than (<) thepitch angle P, the CPU 31 judges that the hull 13 is being loaded ontothe trailer 40 even if a state in which a predetermined opening angle isless than (<) the throttle opening angle TH has continued for apredetermined period of time.

According to the eighth method, based on the engine rpm N and the pitchangle P of the hull 13, the CPU 31 judges whether or not the hull 13 isbeing loaded onto the trailer 40. Specifically, when a predeterminedpitch angle is less than (<) the pitch angle P, the CPU 31 judges thatthe hull 13 is being loaded onto the trailer 40 even if a state in whicha predetermined rpm is less than (<) the engine rpm N has continued fora predetermined period of time.

It should be noted that one of the methods described above may be used,or the methods described above may be used in combination asappropriate. Besides, the marine vessel 11 may be equipped with acamera, and based on an image (an image of the hull 13, the surface ofthe sea, or the like) shot by this camera, the CPU 31 may judge whetheror not the hull 13 is being loaded onto the trailer 40. It should benoted that the marine vessel 11 may be equipped with an automatictrailering function to automatically load the hull 13 onto the trailer40 and transport it by the trailer 40. In the case in which the marinevessel 11 is equipped with the automatic trailering function, the CPU 31may judge that the hull 13 is being loaded onto the trailer 40 inresponse to an operation that enables the automatic trailering functionto be performed (for example, turning-on of a button for the automatictrailering function). It should be noted that in the variety of methodsdescribed above, a threshold value for use in a judgment whether greateror less may vary depending on the method used.

When the CPU 31 judges in the step S101 that the hull 13 is being loadedonto the trailer 40, the process proceeds to step S103, and when the CPU31 judges that the hull 13 is not being loaded onto the trailer 40, theprocess proceeds to step S102. In the step S103, the CPU 31, whichincludes a processor, controls the trim tab actuators 22A and 22B of therespective trim tab units 20A and 20B to position the respective tabs21A and 21B at the retracted positions. This prevents the tabs 21A and21B from coming into contact with the rail 41 of the trailer 40 or thelike.

It should be noted that even in a case in which the tabs 21A and 21Bhave already been positioned at the retracted positions before they areactuated, the CPU 31 may control the trim tab actuators 22A and 22B toactuate the tabs 21A and 21B to the retracted positions. It should benoted that the marine vessel 11 may be provided with sensors that detectthe swing positions of the tabs 21A and 21B. In the case in which themarine vessel 11 is equipped with such sensors, the CPU 31 may controlthe trim tab actuators 22A and 22B to actuate the tabs 21A and 21Btoward the retracted positions only when the detected swing positions ofthe tabs 21A and 21B do not agree with the retracted positions.

Then, in step S104, the CPU 31 carries out “other processes”. As theother processes, processes are carried out according to, for example,settings made and operations performed with the setting operation unit19. Also, in response to the maneuvering system being stopped, a processthat ends this flowchart is carried out. It should be noted that modesset using the setting operation unit 19 may include an “automaticposture control mode”. This automatic posture control mode is a mode inwhich an automatic posture control function which is a control functionof the controller 30 and in which the tabs 21A and 21B are moved so asto control the posture of the hull 13 during sailing is enabled. Withthe automatic posture control function, the tabs 21A and 21B are loweredto cause the hull 13 to produce a lift force so that the posture of thehull 13 can be changed or stabilized as disclosed in, for example,Japanese Laid-Open Patent Publication (Kokai) No. 2009-262588. It shouldbe noted that when the CPU 31 judges that the hull 13 is being loadedonto the trailer 40, the process to control the trim tab actuators 22Aand 22B to position the respective tabs 21A and 21B at the retractedpositions is carried out in the step S103 irrespective of whether or notthe automatic posture control function is being executed. After the stepS104, the process returns to the step S101.

In the step S102, the CPU 31, which defines and functions as a detectionunit, judges whether or not the hull 13 has entered a speed restrictionzone. For example, map information (or nautical chart information) isstored in the ROM 32 in advance. The map information includesinformation on the speed restriction zone. The CPU 31 obtains a presentposition of the hull 13 from a GPS signal received by the receiver 39.Referring to the map information, the CPU 31 judges whether or not thehull 13 has entered the speed restriction zone based on the presentposition. Alternatively, the CPU 31 judges that the hull 13 has enteredthe speed restriction zone when the receiver 39 has received anidentification signal received from the speed restriction zone or landin the vicinity of the speed restriction zone.

When the CPU 31 judges in the step S102 that the hull 13 has entered thespeed restriction zone, the process proceeds to the step S103. When theCPU 31 does not judge that the hull 13 has entered the speed restrictionzone, the process proceeds to the step S104. As a result of proceedingfrom the step S102 to the step S103, the tabs 21A and 21B are positionedat the retracted positions in the speed restriction zone. This isbecause the speed restriction zone is assumed to be shallow water, andthus from the viewpoint of avoiding contact with a foreign object suchas the sea bottom, the tabs 21A and 21B are preferably raised to theretracted positions, and in addition, there is a possibility that thehull 13 will be loaded onto the trailer 40. Moreover, another reason isthat usually the hull 13 does not sail at high speed in the speedrestriction zone, and thus the necessity to control the posture of thehull 13 by lowering the tabs 21A and 21B is small.

According to the present preferred embodiment, upon judging that thehull 13 is being loaded onto the trailer 40, the CPU 31 controls thetrim tab actuators 22A and 22B to position the tabs 21A and 21B, whichare posture control tabs, at the retracted positions. This prevents thetabs 21A and 21B from coming into contact with a foreign object such asthe trailer 40.

Moreover, upon detecting that the hull 13 has entered the speedrestriction zone, the CPU 31 controls the trim tab actuators 21A and 21Bto position the tabs 21A and 21B at the retracted positions even if thehull 13 is not being loaded onto the trailer 40. This prevents the tabs21A and 21B from coming into contact with a foreign object such as thesea bottom, the ground, or the trailer 40. It should be noted that it isnot necessary to include both of the steps S101 and S102 in theflowchart in FIG. 5. If the step S101 is omitted, the CPU 31 controlsthe trim tab actuators 21A and 21B to position the tabs 21A and 21B atthe retracted positions when it has detected that the hull 13 hasentered the speed restriction zone irrespective of whether the hull 13is being loaded onto the trailer 40.

It should be noted that as the posture control tabs, interceptor tabsmay be used in place of the tabs 21A and 21B. Each of the interceptortabs changes its position from a position at which it projects from abottom surface (the vessel bottom) of the hull 13 to a position which isabove the bottom surface of the hull 13.

It should be noted that the setting operation unit 19 may be configuredto make a setting as to whether or not to carry out the trim tabretracting process, which was described with reference to FIG. 5, whenthe maneuvering system is activated.

It should be noted that the number of outboard motors mounted on thehull 13 may be one or three or more. Also, the hull 13 may be equippedwith three or more trim tab units. Marine vessels to which preferredembodiments of the present invention are applicable are not limited tothose equipped with outboard motors, but the present invention is alsoapplicable to marine vessels equipped with other types of marinepropulsion devices such as inboard/outboard motors (stern drive, inboardmotor/outboard drive), inboard motors, and water jet drive.

While preferred embodiments of the present invention have been describedabove, it is to be understood that variations and modifications will beapparent to those skilled in the art without departing from the scopeand spirit of the present invention. The scope of the present invention,therefore, is to be determined solely by the following claims.

What is claimed is:
 1. A control system comprising: posture control tabsmounted on a stern of a marine vessel to control a posture of a hull ofthe marine vessel; actuators to actuate the posture control tabs; and acentral processing unit configured or programmed to define and functionas: a judgment unit to judge whether or not the hull is being loadedonto a trailer; and a processor to, upon the judgment unit judging thatthe hull is being loaded onto the trailer, control the actuators toposition the posture control tabs at retracted positions; wherein thejudgment unit judges that the hull is being loaded onto the trailer whenconditions that a speed of the hull is less than a predetermined speed,and a predetermined pitch angle is less than a pitch angle of the hullare satisfied; the judgment unit judges that the hull is being loadedonto the trailer when conditions that the speed of the hull is less thanthe predetermined speed, and a predetermined engine rpm is less than anumber of engine revolutions of a propulsion device including an engineare satisfied; the judgment unit judges that the hull is being loadedonto the trailer when the speed of the hull has not exceeded thepredetermined speed for a predetermined period of time since a throttleopening angle of the propulsion device became greater than apredetermined opening angle; the judgment unit judges that the hull isbeing loaded onto the trailer when conditions that an acceleration ofthe hull is less than a predetermined acceleration, and thepredetermined pitch angle is less than a pitch angle of the hull aresatisfied; the judgment unit judges that the hull is being loaded ontothe trailer when conditions that the acceleration of the hull is lessthan the predetermined acceleration, and the predetermined engine rpm isless than the number of engine revolutions of the propulsion device aresatisfied; the judgment unit judges that the hull is being loaded ontothe trailer when the acceleration of the hull has never exceeded thepredetermined acceleration for a predetermined period of time since thethrottle opening angle of the propulsion device became greater than thepredetermined opening angle; the judgment unit judges that the hull isbeing loaded onto the trailer when the predetermined pitch angle is lessthan the pitch angle of the hull, even if a state in which thepredetermined opening angle is less than the throttle opening angle ofthe propulsion device has continued for a predetermined period of time;or the judgment unit judges that the hull is being loaded onto thetrailer when the predetermined pitch angle is less than the pitch angleof the hull, even if a state in which the predetermined engine rpm isless than the number of engine revolutions of the propulsion device hascontinued for a predetermined period of time.
 2. The control systemaccording to claim 1, wherein the processor performs an automaticposture control function to move the posture control tabs so as tocontrol a posture of the hull during sailing; and upon the judgment unitjudging that the hull is being loaded onto the trailer, the processorcontrols the actuators to position the posture control tabs at theretracted positions irrespective of whether or not the automatic posturecontrol function is being executed.
 3. The control system according toclaim 1, wherein the central processing unit is configured or programmedto define and function as a detection unit to detect whether or not thehull has entered a speed restriction zone; and upon the detection unitdetecting that the hull has entered the speed restriction zone, theprocessor controls the actuators to position the posture control tabs atthe retracted positions even in a case in which the judgment unit judgesthat the hull is not being loaded onto the trailer.
 4. The controlsystem according to claim 3, wherein the detection unit obtainspositional information, and detects whether or not the hull has enteredthe speed restriction zone based on the obtained positional informationand map information.
 5. The control system according to claim 3, furthercomprising: a receiver to receive an identification signal transmittedin the speed restriction zone; wherein upon the receiver receiving theidentification signal, the detection unit detects that the hull hasentered the speed restriction zone.
 6. A marine vessel comprising: ahull; and a control system including: posture control tabs mounted on astern to control a posture of the hull; actuators to actuate the posturecontrol tabs; and a central processing unit configured or programmed todefine and function as: a judgment unit to judge whether or not the hullis being loaded onto a trailer; and a processor to, upon the judgmentunit judging that the hull is being loaded onto the trailer, control theactuators to position the posture control tabs at retracted positions;wherein the judgment unit judges that the hull is being loaded onto thetrailer when conditions that a speed of the hull is less than apredetermined speed, and a predetermined pitch angle is less than apitch angle of the hull are satisfied; the judgment unit judges that thehull is being loaded onto the trailer when conditions that the speed ofthe hull is less than the predetermined speed, and a predeterminedengine rpm is less than a number of engine revolutions of a propulsiondevice including an engine are satisfied; the judgment unit judges thatthe hull is being loaded onto the trailer when the speed of the hull hasnot exceeded the predetermined speed for a predetermined period of timesince a throttle opening angle of the propulsion device became greaterthan a predetermined opening angle; the judgment unit judges that thehull is being loaded onto the trailer when conditions that anacceleration of the hull is less than a predetermined acceleration, andthe predetermined pitch angle is less than a pitch angle of the hull aresatisfied; the judgment unit judges that the hull is being loaded ontothe trailer when conditions that the acceleration of the hull is lessthan the predetermined acceleration, and the predetermined engine rpm isless than the number of engine revolutions of the propulsion device aresatisfied; the judgment unit judges that the hull is being loaded ontothe trailer when the acceleration of the hull has never exceeded thepredetermined acceleration for a predetermined period of time since thethrottle opening angle of the propulsion device became greater than thepredetermined opening angle; the judgment unit judges that the hull isbeing loaded onto the trailer when the predetermined pitch angle is lessthan the pitch angle of the hull, even if a state in which thepredetermined opening angle is less than the throttle opening angle ofthe propulsion device has continued for a predetermined period of time;or the judgment unit judges that the hull is being loaded onto thetrailer when the predetermined pitch angle is less than the pitch angleof the hull, even if a state in which the predetermined engine rpm isless than the number of engine revolutions of the propulsion device hascontinued for a predetermined period of time.
 7. A method forcontrolling posture control tabs of a marine vessel including posturecontrol tabs mounted on a stern to control a posture of a hull, andactuators to actuate the posture control tabs, the method comprising:judging with a judgment unit whether or not the hull is being loadedonto a trailer; and upon the judgment unit judging that the hull isbeing loaded onto the trailer, controlling with a processor theactuators to position the posture control tabs at retracted positions;wherein the judgment unit judges that the hull is being loaded onto thetrailer when conditions that a speed of the hull is less than apredetermined speed, and a predetermined pitch angle is less than apitch angle of the hull are satisfied; the judgment unit judges that thehull is being loaded onto the trailer when conditions that the speed ofthe hull is less than the predetermined speed, and a predeterminedengine rpm is less than a number of engine revolutions of a propulsiondevice including an engine are satisfied; the judgment unit judges thatthe hull is being loaded onto the trailer when the speed of the hull hasnot exceeded the predetermined speed for a predetermined period of timesince a throttle opening angle of the propulsion device became greaterthan a predetermined opening angle; the judgment unit judges that thehull is being loaded onto the trailer when conditions that anacceleration of the hull is less than a predetermined acceleration, andthe predetermined pitch angle is less than a pitch angle of the hull aresatisfied; the judgment unit judges that the hull is being loaded ontothe trailer when conditions that the acceleration of the hull is lessthan the predetermined acceleration, and the predetermined engine rpm isless than the number of engine revolutions of the propulsion device aresatisfied; the judgment unit judges that the hull is being loaded ontothe trailer when the acceleration of the hull has never exceeded thepredetermined acceleration for a predetermined period of time since thethrottle opening angle of the propulsion device became greater than thepredetermined opening angle; the judgment unit judges that the hull isbeing loaded onto the trailer when the predetermined pitch angle is lessthan the pitch angle of the hull, even if a state in which thepredetermined opening angle is less than the throttle opening angle ofthe propulsion device has continued for a predetermined period of time;or the judgment unit judges that the hull is being loaded onto thetrailer when the predetermined pitch angle is less than the pitch angleof the hull, even if a state in which the predetermined engine rpm isless than the number of engine revolutions of the propulsion device hascontinued for a predetermined period of time.